is there still no option to report posts on DN?

You should take a look at hood.ie it's a library that abstracts away a lot of backend logic and is easy to use in the frontend.

For a website, I'd always prefer building the front-end myself.

For mobile, sitting together with your developer is the best you can do. It's not only that both of you get to learn the other's workflow but you're also woking faster (solving problems together, not slicing stuff that is going to get hardcoded anyways, no back and forth e-mailing about how a certain feature should be implemented) while building a higher quality product. I always try to slice the assets in advance and give them self-explanatory names (Area-ElementInCamelCase-State@2x.png; for example: Profile-FollowButton-Tap@2x.png) in case the dev is on his own. When working in a team that I trust I also send the dev my properly annotated PSD with LayerComps for each screen because for many things like colour or size it's just faster and easier picking them out of the PSD.